Howdy there. After investigating my brake system rather thoroughly,
Ihave found that in addition to a bunch of other things, the pedal  is
indeed not returning to its proper position. HAving sprayed the rusty
spring liberally with PB Blaster, and still not bettering things, I
wonder what else I can do? 
I did, however, replace one rear cylinder, and rebuild the other. (I had
actually bought 2 new ones, but one, although in the correct box, was
the &&^%$##%^&*& wrong size. I was rather perturbed at that, but stores
were closed by this point.) I also put in a new Master Cylinder, and was
tightening a compression fitting, which overtightened, and cracdked.
*&%#!@%^^#&^%&*^$
oh well, that's always how it goes. Luckily, time is on my side for now.
Anyway, this is on a '67 bus, with a limp brake pedal...
thanks